It is the objective of this project to develop microwave exposure systems for bioeffects research and to develop and test techniques for measuring energy absorption. Waveguide systems for exposing cell preparations, which allow stirring during exposure have been developed. These systems also have the capability of controlling temperature at any desired level between 10 degrees C and 60 degrees C. The systems operate at 2450 MHz and are capable of providing specific absorption rates (SAR's) from 0 to 100 mW/g using continuous wave radiation and 0-30 mW/g using pulse wave radiation. A small three-axis electric field probe has been obtained from Narda Corporation and is in the process of being tested for its utility in measuring electric fields in biological material.